Implant systems using an elastic cushion are known in which an implant body in the jaw of the patient has an elastic cushion member, namely, a so-called intramobile element, screwed into it and composed of a synthetic resin material. This intramobile element generally has the form of a cylindrical bushing or boss. The cushioning element is surrounded by a spacing sleeve which is braced on the one hand upon the implant body and on the other hand on a flange on the upper end of the intramobile element. In a central threaded bore of the cushion element, a so-called implant post is threaded and serves to attach the connecting member of the crown to the implant structure. This connecting member can have a threaded pin which can be screwed into an internal thread of the implant post.
This known implant system has the drawback that, upon deformation of the elastic member in the radial direction, gaps and/or microscopic hollow spaces are formed which can become filled with contaminants and enable bacteria to establish themselves in the peri-implant region with the result that the gum tissue around the implant becomes unstable and the tissue which, under the most desirable conditions should reform and develop actively around the implant, does not.
On a long term basis this can lead to infection, bone loss and even destructive loss of the implant and hence the prosthesis.
While it may be conjectured that placing the elastic member under a certain degree of prestress would suffice to prevent the development of gaps and the like with negative results, in practice it is found that this approach does not reliably eliminate the problem since the prestress cannot be maintained because of the natural creep of the elastic synthetic resin material.